1. Field of the Invention
Subject matter of the present invention is a water-soluble, solid contact lens care agent.
2. The Prior Art
Contact lenses are much in demand with individuals suffering from ametropia. Still, one problem with the use of contact lenses is the correct care thereof. There is known a multitude of different systems having essentially in common that a disinfection of the contact lens is effected after wearing the contact lens, usually during the night, where disinfection is effected by chemicals which have to be neutralized subsequently due to the aggressive character thereof. For this purpose a multiplicity of care agents has been successful on the market, e.g., an aqueous hydrogen peroxide solution as disinfecting solution which is neutralized or decomposed by subsequent steps. To this end, several systems such as the catalytic decomposition on precious metal surfaces, the enzymatic decomposition using, e.g., catalase, and the chemical neutralization by reduction of the hydrogen peroxide by sodium thiosulfate are known in the art. The problem of removing metabolic deposits, in particular protein deposits on the lenses or within the lens material, has in principle been solved in the art as well. For this, e.g., agents containing protease are added during a preliminary cleaning step. In particular, subtilisin has to be mentioned as a protease removing any protein deposits within the matrices of soft contact lenses. The state of the art is represented by EP 0 219 220. There, a combined contact lens care agent is described which both disinfects and cleans the contact lenses. In this case, a solution of hydrogen peroxide and a protease being active in a peroxide-containing solution effects disinfection. As a suitable protease subtilisin is mentioned.
Removing any metabolic deposits, in particular protein deposits, within the contact lens matrices is extremely important as these deposits result in changes of the lens matrix including changes of the optical properties and the generation of inflammations.
Although various systems have been available in the market, caring especially for soft contact lenses seems to be so complicated that recently so-called one-way contact lenses have been marketed increasingly. Here, cleaning and disinfecting is no longer in the fore as the contact lenses are simply disposed after a certain wearing time. On the other hand, this results in the fact that only ready-made, mass-produced articles can be offered as any individual adaption of the contact lens is too costly, so that an individually adapted one-way lens will be unattainable. However, when dispensing with individual adaptions patients are provided with contact lenses lacking optimal properties, so that such a way of proceeding is not advisable from the physiological point of view.
The state of the art is especially detrimental in that proteases are usually employed in a separate cleaning step which is arranged prior to the disinfection. Because of this a high willingness of the user to perform the cleaning and disinfection correctly is demanded. After performing the cleaning using proteases, this protease solution usually is discarded and subsequently a separate disinfection phase is performed. This two-stage process is often considered to be cumbersome by users and promotes an improper mode of behavior due to a negligent use. Thus, for example, it may happen that the disinfecting step is forgotten and the lens is put on directly from the protease solution. In a different method a protease is added to the disinfecting solution, said protease, however, being added in such a high amount that the protease has to be eliminated by a physiological solution after the cleaning step. Otherwise, too much protease would remain within the contact lens matrix possibly resulting in irritations on the user's eye.